High strength, hot corrosion and oxidation resistant, equiaxed nickel base superalloy and articles and method of making

ABSTRACT

Corrosion and oxidation resistant, high strength, directionally solidified superalloy alloys and articles are described. The articles have a nominal composition in weight percent of about 12.1% Cr, 9% Co, 1.9% Mo, 3.8% W, 5% Ta, 3.6% Al, 4.1% Ti, 0.013% B, 0.1 % C, up to about 0.01 Zr, balance essentially nickel. The resultant articles have good hot corrosion resistance, oxidation resistance and creep properties. The articles are preferably cast as equiaxed articles such as gas turbine engine components.

CROSS REFERENCE TO RELATED APPLICATION

[0001] Some of the material described herein is described and/or claimedin co-pending and commonly owned application Ser. No. 10/023,565entitled “HIGH STRENGTH, HOT CORROSION AND OXIDATION RESISTANT,DIRECTIONALLY SOLIDIFIED NICKEL BASE SUPERALLOY AND ARTICLES”, which isexpressly incorporated by reference herein.

TECHNICAL FIELD

[0002] The present invention relates to the field of nickel basesuperalloys for use in equiaxed articles, and more particularly to suchalloys providing articles having good mechanical properties at elevatedtemperatures, good resistance to hot corrosion, and good oxidationresistance.

BACKGROUND OF THE INVENTION

[0003] The increasing demands for efficiency in gas turbine engines haveresulted in a demand for materials capable of withstanding more severeoperating conditions. In particular, good strength is required forcertain applications along with the resistance to hot corrosion,oxidation and creep.

[0004] U.S. Pat. No. 3,619,182 describes a moderate strength superalloy,commercially known as IN 792, having purportedly superior corrosionresistance. The '182 patent describes an alloy having a composition, inweight percent, of: 9.5-14 Cr; 7-11 Co; 1-2.5 Mo; 3-4 W; 1-4 Ta; up to 1Cb; 3-4 Al; 3-5 Ti; Al+Ti=6.5-8; 0.005-0.05 B; 0.01-0.25 Zr; 0.02-0.25C; bal. Ni. At the time the '182 application was filed, the alloy wouldhave been cast to form an equiaxed (e.g., no indication ofcrystallographic orientation) article, e.g., for gas turbine enginecomponents. The '182 patent is expressly incorporated herein byreference.

[0005] An alloy, commonly known as GTD-111 which has been cast inequiaxed and directionally solidified forms. In equiaxed castings,GTD-111 has a nominal composition, in weight percent, of: 14 Cr; 9.7 Co;1.5 Mo; 3.8 W; 3 Ta; 3 Al; 0.10 C; 5 Ti; 0.02 B; 0.04 Zr, bal. Ni. See,e.g., Schilke, et el. “Advanced Materials Propel Progress in Land-BasedGas Turbines”, Advanced Materials and Processes, April 1992, page______; and U.S. Pat. No. 6,416,596; see also, U.K. Patent GB 1,511,562(13.7-14.3 Cr; 9-10 Co; 1-1.5 Mo; 4.8-5.5 Ti; 2.8-3.2 Al; 3.7-4.3 W;1-1.5 Nb; 2.5-3 Ta; 2.8-3.2 Al; 0.08-0.2 C; 4.8-5.5 Ti; 0.01-0.02 B;0.02-0.1 Zr; and either 1.5-3.5 mixture of Ta, Cb and Hf, or 2.5-3 Ta or2-2.5 Hf or 1-1.5 Cb [or Ta+Cb+Hf=1.5-3.5]; and consisting of a matrixand a monocarbide phase distributed through the matrix consisting of:Ti, Mo, W and/or Ta and/or Cb and/or Hf in proportions such that thetotal of Mo and W is less than 15 weight percent of the carbide phase);see also U.S. Pat. No. 6,428,637. In directionally solidified castings,the nominal composition is similar except for slightly lower amounts ofzirconium. See, G. K. Bouse, “Eta (η) and Platelet Phases in InvestmentCast Superalloys”, presented at Superalloys 1996, Seven Springs, Pa.

[0006] U.S. Pat. No. 3,615,376 is directed to an alloy with a claimedcomposition, in weight percent, of: 0.15-0.3 C (described as more thanis required for de-oxidation and sufficient to form grain boundarycarbides); 13-15.6 Cr; 5-15 Co; 2.5-5 Mo; 3-6 W; 4-6 Ti; 2-4 Al;0.005-0.02 Zr; balance Ni and incidental impurities; and also requiresthat Ti/Al be 1:1-3: 1; Ti +Al between 7.5-9; Mo+0.5W between 5-7; witha substantial absence of sigma phase and a stress rupture life of atleast 25 hours at 27.5 ksi at 1800° F. A directionally solidifiedversion of this alloy may also include a significant, intentionallyadded amount of Hf, e.g. up to or over 0.5 wt. %.

[0007] U.S. Pat. No. 6,231,692 is directed to a nickel base alloy withimproved machinability. The alloy has a composition in weight percent of12.5-15 Cr, 5-15 Co, 2.5-5 Mo, 3-6 Al, 4-6 Ti, 0.005-0.02 B, up to about0.01 Zr, 0.055-0.075 C (“below about 0.08”), balance essentially Ni. Thepatent asserts that the alloy is easier and quicker to machine relativeto Rene 80 alloy.

[0008] It would be desirable to provide a material for the fabricationof equiaxed articles, and to provide such articles, which have adequatestrength, and which also demonstrate good oxidation and corrosionresistance.

[0009] It would also be desirable to provide the benefits of an alloycomposition adapted for use as in cast equiaxed parts which maintain thebenefits of the alloy.

[0010] It would likewise be desirable to provide such an alloy whichprovides oxidation resistance in equiaxed grain form at least comparableto that in directionally solidified form.

SUMMARY OF THE INVENTION

[0011] Alloys for equiaxed solidified articles are disclosed which haveat least comparable oxidation resistance relative to directionallysolidified counterparts, and corrosion resistance at least comparable tosuch alloys. Moreover the inventive alloys have oxidation resistancegreater than directionally solidified counterparts, and comparablecorrosion resistance. In many instances, the alloys of the presentinvention provide articles in equiaxed form with superior oxidationresistance.

[0012] The inventive alloys comprise, in weight percent, of about11-13.25% chromium; 8-10% cobalt; 1.5-2.5% molybdenum; 3.25-4.5%tungsten; 4.5-5.5% tantalum; 3.25-4% aluminum; 3.5-4.5% titanium;0.005-0.02% boron; up to about 0.03% zirconium; 0.05-0.2% carbon; up toabout 0.15% hafnium; and balance essentially nickel; and in anothervariation about 11-13% chromium; 8.25-9.75% cobalt; 1.5-2.25%molybdenum; 3.4-4.3% tungsten; 4.7-5.5% tantalum; 3.3-4% aluminum;3.75-4.3% titanium; 0.008-0.02% boron; up to about 0.03% zirconium;0.05-0.15% carbon; up to about 0.15% hafnium; and balance essentiallynickel.

[0013] In equiaxed form, the alloy exhibits oxidation resistance at2000° F. of at least roughly 2.5×, creep rupture life at 1400° F. of atleast roughly 2.5×, at 1600° F. of at least roughly 2×, and at 1800° F.of at least roughly 1.3× compared to a similar article having acomposition of equiaxed GTD 111 nominally composed of 14 Cr, 4.9 Ti, 1.6Mo, 3.8 W, 2.8 Ta, 3 Al, 9.5 Co, 0.01 B, 0.02 Zr, 0.1 C, and balance Ni.

[0014] The invention composition may be cast in equiaxed form accordingto the teachings of various prior patents as is known in the art. Whereneeded, the present composition after being cast can be heat treated inorder to improve the mechanical properties of the alloy by controllingthe gamma prime particle size in accordance, e.g., with the teachings ofU.S. Pat. No. 4,116,723 which is also expressly incorporated herein byreference. Such parts, for example for industrial gas turbines may bequite large, on the order or up to about 60 inches long, although mostparts such as blades and vanes are between about 5-50 inches long.

[0015] Other features and advantages will be apparent from thespecification and claims which illustrate an embodiment of theinvention.

BRIEF DESCRIPTION OF DRAWINGS

[0016]FIG. 1 is a graph illustrating creep rupture life of the inventivealloy versus a prior art equiaxed alloy.

[0017]FIG. 2 is a graph illustrating the relative creep rupture life ofthe inventive alloy at 1800 F.

[0018]FIG. 3 is a graph illustrating the relative creep rupture life ofthe inventive alloy at 1600 F.

[0019]FIG. 4 is a graph illustrating the relative creep rupture life ofthe inventive alloy at 1400 F.

[0020]FIG. 5 is graph illustrating the effect of aluminum and hafniumcontent on oxidation resistance of the inventive alloy.

[0021]FIG. 6 is a graph illustrating the relative hot corrosionresistance of the inventive alloy.

[0022]FIG. 7 is a graph illustrating the relative oxidation resistanceof the inventive alloy.

[0023]FIG. 8 is a graph illustrating the creep life and oxidation lifefor several hot corrosion resistant alloys.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] The present invention is based on altering the chemistryoriginally adapted for use in single crystal articles, e.g., commonlyowned U.S. Pat. No. 4,597,809 and co-pending, commonly owned applicationSer. No. 10/023,565 entitled “HIGH STRENGTH, HOT CORROSION AND OXIDATIONRESISTANT, DIRECTIONALLY SOLIDIFIED NICKEL BASE SUPERALLOY AND ARTICLES”which are expressly incorporated by reference herein, into an alloy thatis particularly useful in the production of equiaxed articles. Inequiaxed form, cast articles in accordance with the present invention,such as gas turbine engine turbine blades and vanes, are characterizedby good hot corrosion resistance, good oxidation resistance, and goodcreep-rupture properties. We also considered the composition of an alloygenerally designated “GTD-111”, see, e.g., GB Pat. No. 1,511,652 andU.S. Pat. No. 6,416,596, which is used in equiaxed and columnar grainforms, and has a nominal composition in weight percent of 14 Cr, 4.9 Ti,1.5 Mo, 3.8 W, 2.8 Ta, 3 Al, 9.5 Co, 0.01 B, -0.02 Zr, -0.1 C, andbalance Ni.

[0025] We believe that beneficial and different properties may beachieved, among other things, by altering the composition of the singlecrystal '809 alloy by significantly increasing the carbon and boronlevels (and allowing a maximum amount of zirconium in the alloy) on onehand, or by altering the nominal content of the equiaxed/columnar grain−111 alloy by significantly increasing tantalum, aluminum and molybdenumcontents, and significantly decreasing the titanium and chromiumcontents on the other hand (e.g., the '562 patent teaches among otherthings high chromium (above 13.7 wt. %); relatively higher cobalt (over9.5 wt. %); that more than 0.02% zirconium is acceptable; and thattantalum over 3-3.5 wt. % will cause unacceptable microstructuralinstability).

[0026] The generally preferred composition of the present inventionconsists essentially of, in weight percent, about 11-13.25% chromium;8-10% cobalt; 1.5-2.5% molybdenum; 3.25-4.5% tungsten; 4.5-5.5%tantalum; 3.25-4% aluminum; 3.5-4.5% titanium; 0.005-0.02% boron;zirconium in impurity levels (less than about 0.025% zirconium);0.05-0.2% carbon; up to about 0.15% hafnium; and balance essentiallynickel. In another variation, the alloy consists of about 11-13%chromium; 8.25-9.75% cobalt; 1.5-2.25% molybdenum; 3.4-4.3% tungsten;4.7-5.5% tantalum; 3.3-4% aluminum; 3.75-4.3% titanium; 0.008-0.02%boron; up to about 0.03% zirconium; 0.05-0.15% carbon; up to about 0.15%hafnium; and balance essentially nickel. The article has advantages overprior art equiaxed alloys, such as creep rupture at 1400° F. of at leastroughly 2.5×, and at 1600° F. of at least roughly 2× compared to asimilar equiaxed article having a nominal composition of 14 Cr, 4.9 Ti,1.6 Mo, 3.8 W, 2.8 Ta, 3 Al, 9.5 Co, 0.01 B, 0.02 Zr, 0.1 C, and balanceNi. More preferably, the alloy comprises about 11-13% chromium; 8.5-9.5%cobalt; 1.6-2.25% molybdenum; 3.25-4.25% tungsten; 4.75-5.25% tantalum;3.25-4% aluminum; 3.75-4.35% titanium; 0.0075-0.02% boron, 0.08-0.015carbon, balance nickel. Preferably, the inventive alloy has a nominalcomposition of about 12% chromium; 9% cobalt; 1.9% molybdenum; 3.8%tungsten; 5% tantalum; 3.6% aluminum; 4.1% titanium; 0.01% boron; 0.01%zirconium; 0.1% carbon; balance essentially nickel.

[0027] We discovered in the course of developing the alloy of the '565application that even small additions of zirconium detrimentallyaffected the castability of directionally solidified parts, particularlylarge parts such as land based gas turbine engine blades. Articleshaving more than about 0.02 wt. % zirconium tended to tear on investmentcasting, during cooling and solidification of the molten material. Whilenot fully understood, the tearing problem was obviated where zirconiumwas present in less than about 0.02 wt. percent. In the case of equiaxedalloys and articles, the inventive composition preferably includes smallintentional additions of zirconium of up to 0.01%, which do notadversely affect castability. Whether or not it is practical to tolerateabout up to about 0.03 wt. %, we prefer less. We prefer that the alloyand articles also include no intentional addition of hafnium, as we havediscovered an unexpected connection between Hf additions and oxidationresistance in low Al containing alloys. As noted in FIG. 5, there is anunexpected relationship or effect of hafnium content on alloys havingrelatively low aluminum content (which effect holds for alloys havingless than about 3.5-4 wt. % and may hold for higher aluminum contents upto about 5 wt. % ). As oxidation resistance is the ability of an alloyto form an adherent alumina scale, and is in part related to aluminumcontent, it is generally more difficult to form an alumina scale onalloys having lower aluminum contents, e.g., less than about 4-5 wt %,and the hafnium does not significantly aid in the formation of analumina scale in these low aluminum alloys. What we did not expect wasthat the presence of hafnium in these low aluminum alloys is in factdetrimental to the formation of alumina scales, and adversely affectoxidation resistance of these low aluminum alloys.

[0028] The articles to be evaluated were investment cast, and then givensimilar heat treatments a primary heat treat at about 2050° F. for 2hours, followed by coating diffusion heat treat at 1975 F for 4 hours,followed by precipitation heat treat at about 1550° F. for 24 hours. Insome cases, articles were solution heat treated at 2150-2200° F. forless time, but showed no significant increase in properties. Thearticles may be finish machined as needed or desired.

[0029] The articles may also include one or more internal passagesthrough which cooling air may be passed to cool the part. Such passagesare well known in the art, and are not further discussed herein. Theinternal passages, and also some or all portions of the external surfaceof the parts may be coated with corrosion and/or oxidation resistantcoatings like aluminides and overlay or MCrAlY coatings. A broadcomposition range for MCrAlY materials, in wt. %, is 10-25% Cr, 5-15 Al,0.1-1.0 Y balance selected from Fe, Ni, and Co and mixtures of Ni andCo. See, e.g., commonly owned U.S. Pat. Nos. 4,585,481 and Re. 32,121both of which are expressly incorporated by reference herein. Additionsof up to 5% each of Hf, Ta or Re, up to 1% of Si and up to 3% each ofOs, Pt, Pd, or Rh may also be made. Table I describes exemplary MCrAlYsthat can be applied by thermal spray processes, by EBPVD processes, byelectroplating and other suitable manners. TABLE I (wt % - ExemplaryMCrAlY Compositions) Ni Co Cr Al Y Hf Si NiCrAlY Bal — 19.5 12.5 .45 — —CoCrAlY — Bal 18 11 .45 — — NiCoCrAlY Bal 23 18 12.5 .3 — — NiCoCrAlYBal 22 17 12.5 .6 .25 .4

[0030] An alternate bond coat is a diffusion aluminide formed bydiffusing aluminum into the substrate surface. Diffusion aluminides arewell known and may be applied using a mixture (termed a pack) containingan aluminum source, such as an aluminum alloy or compound, an activator(usually a halide compound such as NaF) and an inert material such asalumina. The part to be coated is buried in the pack and heated to1500-2000° F. while a carrier gas, such as hydrogen, is flowed throughthe pack. Out of pack processes, during which the part is not buried inthe pack, are also known. The incorporation of precious metals such asPt, Rh, Pd and Os into aluminide coatings is known. See, e.g., U.S. Pat.No. 5,514,482 for a description of aluminide coating processes.

[0031] Combinations of overlay and aluminide coatings are also possible.See, commonly owned U.S. Pat. No. 4,897,315 for a description of asystem having an inner MCrAlY overlay coating and an outer aluminidecoating. See, commonly owned U.S. Pat. No. 4,005,989 for a descriptionof the reverse combination, an inner aluminide coating and an outeroverlay coating. The common feature of these bond coats and bond coatcombinations is that they form an adherent layer of alumina on theirouter surface. The parts may then-be coated with a ceramic thermalbarrier coating, the composition and application of which are well knownin the art.

[0032] The following data were generated using test bars cast from thereferenced alloys as described above, and were tested in a non-HIP'dcondition. INVENTION 0 wt. % Zr INVENTION .02 Zr GTD 111 Time Time TimeRupture to 1% Rupture to 1% Rupture to 1% Test Life Creep Elong LifeCreep Elong Life Creep Elong Cond. Hours Hours % Hours Hours % HoursHours % 1400F/ 910.3 260 5.6 535.6 111 5.4 115.9 83 2.0 85 ksi 611.9 1954.6 517.3 107 4.5 186.0 71 3.4 288.5 170 2.1 AVE 761.0 227.5 5.1 447.1129 4.0 151.0 77 2.7 1600F/ 342.3 102 4.6 260.8 75 7.2 127.1 45 6.3 50ksi 313.2 99 4.5 202.7 65 5.3 306.3 73 6.0 299.2 82 6.4 AVE 320.6 91 5.0254.2 74 6.3 127.1 45 6.3 1800F/ 91.5 4.3 95.2 48 7.1 50.5 22 6.5 27 ksi87.0 4.0 73.1 45 4.5 70.0 35 7.0 63.7 36 3.7 80.3 55 3.4 AVE 80.7 50 4.082.9 49 5.0 60.3 28.5 6.8

[0033] As is also shown by the data above, FIG. 1 shows some of thebenefits of the inventive equiaxed alloy over equiaxed GTD-111. As shownin the FIG., the inventive alloy exhibits superior creep ruptureresistance at 1400 F, 1600 F and 1800 F. The time to produce 1% creepwas tested in specimens at 1400° F. with an applied stress of 85 ksi, at1600 F with an applied stress of 50 ksi, and at 1800° F. with an appliedstress of 27 ksi. Again, the inventive alloy exhibited creep rupturelives exceeding the equiaxed −111 alloy. In the case of equiaxedarticles, we observed no noticeable effect on creep rupture propertiesof Zr content of 0 and 0.02 wt. %.

[0034]FIG. 6 shows the relative hot corrosion resistance of theinventive alloy compared to other alloys, including the −111 alloy.Corrosion testing was performed at 1650° F. in a corrosion gaseousenvironment produced by combustion of Jet A fuel (30:1 air fuel ratio)with addition of 20 ppm of ASTM sea salt and sufficient sulfur dioxideto produce a sulfur content equivalent to a 1.3% S content in the fuel.The numbers presented are the hours of exposure required to produce 1mil of corrosive attack. As seen in the FIG., the inventive alloyexhibits corrosion resistance comparable to GTD-111 and significantlybetter than single crystal alloys of similar compositions, see, commonlyowned U.S. Pat. Nos. 4,209,348 and 4,719,080 both of which are expresslyincorporated by reference herein.

[0035]FIG. 7 shows the relative uncoated, burner rig oxidationresistance of the inventive alloy at 2000° F. and several other alloys.While the oxidation resistance exceeds the oxidation resistance ofGTD-111 and Rene 80, the inventive alloy is significantly higher (atleast 2.5×) and similar to the oxidation resistance of the singlecrystal alloy of the '809 patent. The increase in aluminum content anddecrease in titanium content of the inventive alloy over GTD-111 islargely responsible for the inventive alloy's greater oxidationresistance.

[0036]FIG. 8 illustrates the relative creep and uncoated oxidation livesof a number of well known hot corrosion resistant alloys. As shown, theinventive alloy combines the best combined oxidation and creep lives ofthese well known alloys. In addition, alloys of the present inventionhave shown to be readily castable by convention methods includinginvestment casting, and in large sizes for parts such as largeindustrial gas turbine parts. Articles formed of the inventive alloycomposition also surprisingly exhibit strengths comparable to those ofangle crystal articles of similar compositions.

[0037] In sum, the present invention is based on a modification of apublished single crystal composition, which in turn was modified tocreated a composition useful in the production of directionallysolidified articles. Beginning with prior art columnar grain or equiaxedcompositions, the present invention includes among other thingssignificantly increasing tantalum, aluminum and molybdenum contents, andsignificantly decreasing the titanium and chromium contents. Theinventive alloy and articles fabricated from the alloy exhibit superiorcombinations of oxidation resistance, corrosion resistance andcreep-rupture resistance at various temperatures.

[0038] It should be understood that the invention is not limited to theparticular embodiments shown and described herein, but that variouschanges and modifications may be made without departing from the spiritand scope of this novel concept as defined by the following claims.

We claim:
 1. A high strength, corrosion and oxidation resistant nickelbase superalloy consisting essentially of, in weight percent, of:11-13.25% chromium; 8-10% cobalt; 1.5-2.5% molybdenum; 3.25-4.5%tungsten; 4.5-5.5% tantalum; 3.25-4% aluminum; 3.5-4.5% titanium;0.005-0.02% boron; up to about 0.03 zirconium; 0.05-0.2% carbon; up toabout 0.15% hafnium; and balance essentially nickel; said article havingcreep rupture at 1400° F. of at least roughly 2.5×, and at 1600° F. ofat least roughly 2× compared to a similar equiaxed article having anominal composition of 14 Cr, 4.9 Ti, 1.6 Mo, 3.8 W, 2.8 Ta, 3 Al, 9.5Co, 0.01 B, 0.02 Zr, 0.1 C, and balance Ni.
 2. An article composed ofthe alloy of claim
 1. 3. The alloy of claim 1 having stress ruptureresistance sufficient to ensure that a load of about 27 ksi appliedruptures after more than about 75 hours, and also has a time to 1% creepof more than 50 hours, at 1800° F.
 4. The alloy of claim 3, whereinstress rupture occurs only after more than 85 hours.
 5. The alloy ofclaim 1, further characterized by having about 11-13% chromium; 8.5-9.5%cobalt; 1.6-2.25% molybdenum; 3.25-4.25% tungsten; 4.75-5.25% tantalum;3.25-4% aluminum; 3.75-4.35% titanium; 0.0075-0.02% boron, and0.005-0.010 zirconium.
 6. The alloy of claim 1, having about 12%chromium; 9% cobalt; 1.9% molybdenum; 3.8% tungsten; 5% tantalum; 3.6%aluminum; 4.1% titanium; 0.01% boron; 0.01% zirconium; 0.1% carbon;balance essentially nickel.
 7. The article of claim 2 comprising a gasturbine engine component.
 8. The article of claim 7, comprising aturbine blade or vane.
 9. A high strength, corrosion resistant, nickelbase superalloy article adapted for use in equiaxed grain articles,comprising in weight percent 11-13.25% chromium; 8-10% cobalt; 1.5-2.5%molybdenum; 3.25-4.5% tungsten; 4.5-5.5% tantalum; 3.25-4% aluminum;3.5-4.5% titanium; 0.005-0.02% boron; less than about 0.03% zirconium;0.05-0.2% carbon; up to about 0.15% hafnium; and balance essentiallynickel; said article having creep rupture at 1400° F. of at leastroughly 2.5×, and at 1600° F. of at least roughly 2× compared to asimilar equiaxed article having a nominal composition of 14 Cr, 4.9 Ti,1.6 Mo, 3.8 W. 2.8 Ta, 3 Al, 9.5 Co, 0.01 B, 0.02 Zr, 0.1 C, and balanceNi.
 10. The article of claim 9 comprising a gas turbine enginecomponent.
 11. The article of claim 10 comprising a turbine blade orvane.
 12. The article of claim 1 having stress rupture resistancesufficient to ensure that a load of about 27 ksi applied ruptures aftermore than about 80 hours, and also has a time to 1% creep of more than40 hours, at 1800° F.
 13. The article of claim 12, wherein stressrupture occurs only after more than 85 hours.
 14. The article of claim9, further characterized by having 11-13% chromium; 8.5-9.5% cobalt;1.6-2.25% molybdenum; 3.25-4.25% tungsten; 4.75-5.25% tantalum; 3.25-4%aluminum; 3.75-4.35% titanium; 0.0075-0.02% boron; 0.01% zirconium. 15.The alloy of claim 14, having about 12% chromium; 9% cobalt; 1.9%molybdenum; 3.8% tungsten; 5% tantalum; 3.6% aluminum; 4.1% titanium;0.01% boron; less than about 0.03% zirconium; 0.1% carbon; balanceessentially nickel.
 16. The article of claim 2 comprising a gas turbineengine component.
 17. The article of claim 16, comprising a turbineblade or vane.
 18. The article of claim 9, wherein the article is up toabout 60 inches long.
 19. A method of producing an equiaxed, cast, highstrength, corrosion resistant, nickel base superalloy article comprisingthe steps of: melting an alloy consisting of in weight percent 11-13.25%chromium; 8-10% cobalt; 1.5-2.5% molybdenum; 3.25-4.5% tungsten;4.5-5.5% tantalum; 3.25-4% aluminum; 3.5-4.5% titanium; 0.005-0.02%boron; less than about 0.03% zirconium; 0.05-0.2% carbon; up to about0.15% hafnium; and balance essentially nickel; and casting the alloy toform an article, wherein the article has creep rupture at 1400° F. of atleast roughly 2.5×, and at 1600° F. of at least roughly 2× compared to asimilar equiaxed article having a nominal composition of 14 Cr, 4.9 Ti,1.6 Mo, 3.8 W, 2.8 Ta, 3 Al, 9.5 Co, 0.01 B, 0.02 Zr, 0.1 C, and balanceNi.
 20. The article of claim 19, further comprising the step ofmachining the article.
 21. The article of claim 19, further comprisingthe step of applying an oxidation and/or corrosion resistant coating tothe article.
 22. The method of claim 21, where in the article has atleast one internal passage, further comprising the step of applying anoxidation and/or corrosion resistant coating to the internal passage.23. The article of claim 9, further comprising a thermal barrier coatingapplied to one or more portions of the article.